Modern life is becoming more dependent upon electronic systems. Electronics devices have evolved into extremely sophisticated devices, and may be found in many different applications. As electronics become more integrated into daily life, their ability to communicate and work together becomes a greater and greater necessity.
Computer devices commonly communicate through networks. These networks can take many shapes and forms. Different network systems communicate with different standards and protocols. One such popular standard is the IEEE 802.3 Ethernet standard. The Ethernet standard provides a low cost-high speed data communication with controllers that are available from a wide range of suppliers. This makes Ethernet controllers a desirable component in high volume communication products.
Unfortunately, there are some limitations in the Ethernet protocols and controllers that limits its applicability. For example, Ethernet controllers use a carrier sense medium access/collision detection mechanism which permits all nodes to access the media. Any node on the network can attempt to contend for the channel by waiting for a predetermined time after the last activity before transmitting on the media. If two nodes simultaneously contend for a channel, the signal will interact and potentially cause a loss of data. This event, called a collision, causes the Ethernet controller to retransmit after a random time period.
Typically, an on-chip buffer is used to store the message until the message can be transmitted again. The controller attempts to transmit when the buffer is filled and the medium is quiet. When there is contention, the controller continues to attempt to transmit the message until it can be done without causing a collision.
While this method is generally very effective, it does have some limitations. One limitation is that it does not allow individual nodes to have precise timing control over its time of transmission. This generally limits bandwidth and makes the Ethernet controller unacceptable for applications that require tight timing control.
For a real time communication system, it is critical for the transmitting node to transmit its message within a tight timing tolerance and no babbling is allowed to interfere with any other node's transmission ability. These criterion are manifested in real time communication protocols such as TDMA (Time Division Multiplexing Access) protocol.
The TDMA protocol requires each node connected to the medium to transmit at a specific non-overlapping time slot to ensure no message collision on the media. Each node has a transmission schedule relative to a global time reference. Once the nodes accomplish synchronization with the global time reference, each node uses the transmission schedule to transmit at its prescribed time slot. This requires tight transmission timing control to ensure transmission starts and completes within its assigned time slot. Additional measures are necessary to prevent a node from “babbling” the media when it is not scheduled to transmit message. The transmission timing control must be tight to better utilize available bandwidth and meet hard real time communication requirements.
Currently, no solutions exist that allow the use of a commonly available Ethernet controller in systems that require tight timing control or protection from “babbling”. Thus, what is needed is an improved system and method for network communication that gives improved timing control to provide a high performance real time transmission system.